Connecter for electric drills



Spt. 29, 1936. KUEHNE 2,055,867

CONNECTER FQR ELECTRIC DRILLS Filed Oct. 7 18, 1935 INVENTOR.

BY 34Pm- Wm,

ATTORNEYS Patented Sept. 29, 1936 UNITED STATES.

PATENT OFFICE common-2a roa ELECTRIC mums Application October 18, 1935, Serial No. 45,545

4 Claims. (o1. 1'l236) This invention relates to relatively small portable electric hand drills oi the gun orrpistol type.

The drill is held in and supported by one hand grasping the drill casing on opposite sides and the single handle at the rear end or the drill. The handle is of the pistol grip type and preferably made hollow to provide an air duct for the cooling system for the electric motor and to accommodate one of the brushes 0! the motor and the connecten-ior electrically attaching said brush to one of the electric supply wires for the tool.

The general purpose and object of my invention is to provide an improved connecter fixture and one which establishes direct connection with the metal conducting sleeve for the brush on fitting connecter with a yieldable contact which directly engages the exposed portionof the metal sleeve on placing the connecter in the handle.

A further object of my invention is to provide the connecter with a binding screw whereby the supply wires which furnish current for the motor of the tool may be readily connected to and disconnected from the connecter without disturbing the connection of the stator wire with the stator oi! the motor. In the accompanying drawing illustrating one embodiment of my invention:

Fig. 1 is a side elevational view of a small portable electric hand drill provided with a connecter of my invention, the handle portion 01' the tool being broken away and in section, respectively, to show the connecter and its associated brush holder; n

Fig. 2 is a sectional view taken through the'handle at the connector and brush holder on line 2-2 ofFlg. 1; and

. Fig. 3 is a perspective view of the connecter fixture removed from the tool.

In the drawing, I indicates the outer casing of the drill enclosing an electric motor which fur nishes the power for rotating the chuck shaft or spindle 2. The motor may be of horseshoe type and arranged in the drill casing with its field coil in the upper part oi the casing I and its armature {in the lower part of said casing as indicated in Fig.- 1. The shaft of the armature extends into a gear case 4 at the front end of the drill'and is provided with gear teeth which mesh with a gear wheel fixed on the chuck shaft 2 which is journaled in the gear case in lateral oflset relation to the armature shaft, as indicated in Fig. 1.

The single handle 5 of the drill is of the pistol rip type. The handle is at the rear end of the drill and extends'below the casing i in approximately right angular relation thereto as shown. The handle 5 is comprised of a forward part 6 5 preferably integral with the casing I and a detachable rear part 1 which provides a removable closure plate on the rear side of the handle for a compartment 8 which the handle forms with the casing l. The handle is made hollow for thispurpose and is provided at its outer or lower end with an opening 8 for the intake of cooling air for the motor and to receive the cable ill containing the electric supply wires ll, 12 for the drill. A part of the opening 9 is embodied in the cover plate 1 whereby the cable may be readily applied to and removed from the drill on taking oil? the cover.

The cover plate 7 is removably secured in place by a screw 13 which takes into a cup support it 20 for the hearing l5 for the rear end of the armature shaft of the motor. Bearing support i4 is carried by the drill case I. The forward end of the armature is journaled in the gear case i.

The commutator -16 of the motor is betweenthe 25 armature 3 and the bearing i5. The brushes H,

M for the motor engage the commutator i6 and these brushes are located, one in the casing I above the commutator and the other in the handle part 6 below the commutator. 30

Each brush is slidably mounted'in a metal supporting tube or sleeve [9. The sleeve has a tight fit in a holder 20 of suitable electrical insulating material. The holder 20 encloses all sides of the metal sleeve except one. The brushes are urged 35 against the commutator by springs, one in each metal sleeve.

The lower brush assembly is mounted in a bore or passage 2| .in the handle part 6 and said passage is closed at this lower end by a screw plug 22 which secures the lower brush holder in place in the handle. This plug is of electrical insulating material and clamps the outer end of the holder 20 against a shoulder in the handle part 5 as shown in Fig. 1. The passage 2| is open 45 along one side into the compartment 8 and the brush holder 20 is so mounted in this passage that the exposed part of its metal tube i9 is exposed along the open side-of the passage as shown in Fig. 2.

Also located in the compartment 8 adjacent the lower brush holder is a connecter comprising an insulating body part 23 which extends across the space between the side walls 01 the compartment as-shown in Fig. 2. The body part '23 is 55 provided with a contact member 24 'slidably mounted in a recess or chamber 25 in the connecter body as shown. The chamber 25 opens through the side of the connecter body opposed to the exposed wall of the metal tube 19 whereby the contact member 24 may readily engage the metal tube. A coil spring 26 located in the recess urges the contact member toward the tube. The contact member at this point has an enlarged head to seat the spring and also bear against the metal tube.

The shank of the contact member 24 extends out of the recess through an opening in the connecter body at the bottom of the recess and is provided at its outer end with a binding screw 21 for connecting the wire i I to the contact member. The head of the contact member 24 and the chamber 25 are non-circular and interilt to hold the contact member against turning. The contact member 24 is located adjacent the lower edge of the connecter body, as shown.

The connecter body also carries a binding screw 28. This screw is above the contact member 24 and extends into a chamber 29 in the connecter body above the chamber 25. The chamber 29 opens through the same side of the connecter body as the chamber 25 and is normally closed at its outer end by an insulating plug or washer 30. The latter flts tightly in thechamber 29 and is preferably flush with the associated outer surface of the connecter body so as not to project beyond the same to prevent the contact member 24 reaching the metal tube l9. Fitted in the chamber 29 is a nut 3| with which the screw 28 engages. The nut 3|, by its lit in the chamber 29, is held against turning and has a tubular portion 32 which extends out of the chamber to the side of the connecter body opposite the insu- .lating plug 30. The outer end of this tubular portion 32 provides a seat for the head of the screw 28 and enables the screw to clamp together the metal terminals at the adjacent ends of the wires i2 and i241. The latter wire leads to the stator of the motor and being separate from the wire l2 enables the binding screw arrangement to provide an easy means by which a new cable may be connected to the tool.

The connecter 23 is preferably fastened in place in the compartment 8 by one or more screws 33 extended through openings 34 in the connecter body and entering tapped holes in the handle part 8 as shown in Fig. 2.

The advantages of the connecter construction shown and described are: The use of a contact member 24 which bears directly against the metal tube l9 of the lower brush holder enables an electrical connection to be made with the brush on merely inserting the connecter in the handle and securing it in place. 'No wires or binding screws are required as heretofore. Moreover, exposing the metal tube of the brush holder along the length of the holder enables the contact to be made without accurate spotting or setting of the contact means. Also the contact being yieldable, compensates for clearances between the parts. Also, the screws 33 when tightened do not exert any strain on the metal sleeve iii to distort it or interfere with the free movement of the brush l1 therein. The binding screw 28 enables a separate wire to be used as the stator wire and'thus the wires of the cable ill may be readily and easily connected to and disconnected from the connecter fixture without disturbing the connec-..

tion of the stator wire i2a with thestator of the The switch device for the. motor is indicated I at 35. This device connects the upper brush with the field coil, and is thumb operated to turn on and of! the current to .the motor. The switch device and its manner of electrical connection with the upper brush holder and the field coil of the motor, respectively, constitute the subjects-matter of the co-pending applications of Frithiof P. Forss, Serial No. 45,541 and Frank B. Hamerly, Serial No. 45,544, both filed October 18, 1935.

The details of construction and arrangement of parts shown. and described may be variously changed and modified without departing from the spirit and scope of my invention, except as set forth in the appended claims.

I claim'as my invention:

1. In a portable electric tool, an outer casing, an electric motor therein, a hollow handle at one end of the casing and extending outwardly therefrom in transverse relation to the axis of rotation of the motor, a brush holder in the handle, a spring biased brush for the motor in the holder, said holder having a metal tube supporting the brush and exposed along its side facing the compartment formed by the hollow handle, a connecter secured in the handle and having a contact member directly engageable with the exposed side of the metal tube on inserting the connecter in the handle, and means for connecting a supply wire to said contact member.

2. In a portable electric tool, an outer casing, an electric motor therein, a hollow handle at one end of the casing and extending outwardly therefrom in transverse relation to'the axis ofrotation of the motor, a brush holder in the handle,

a spring biased brush for the motor in the holder, said holder having a metal tube supporting the brush and exposed along its side facing the compartment formed by the hollow handle, a

connecter secured in the handle and having a spring pressed contact member slidably mounted in the connecter and directly engageable at one end with the exposed side of the metal tube on inserting. the connecter in the handle, and means for connecting a supply wire to the opposite end of said contact member.

3. In a portable electric tool of the character described, an outer casing, an electric motor therein, a hollow handle at one end of the easing and extending outwardly therefrom in transverse relation to the axis of rotation of the motor, a brush holder in the handle, a spring biased brush for the motor in said holder, said holder having a metal tube supporting the brush and exposed along its side facing the compartment formed by the hollow handle, a connecter having, a brush holder in the handle, said holder having an outer case of insulating material seated in a passageway in the handle and a metal tube in said case, a spring biased brush to: the motor in said tube, said casing being open along one side to expose the metal tube to the compartment formed by the hollow handle, a conne'cter in the handle over the holder at the, exposed side of the tube, means for securing the connector in the handle beyond the sides of the holder, a. spring pressed contact member slidably mounted in the eonnecter and directly engageable at one end with the exposed side of the tube, and means at the other end of the contact member for connecting a supply wire thereto.

HERMAN KUE'I-DIE. 

